The present invention relates to a looper for use in a tufting machine for manufacturing carpets.
FIG. 6 shows a conventional looper 1 which includes a hook throat portion 2 having a bottom edge 3. Loops B are formed on a backing cloth A by moving the looper 1 back and forth as shown by arrows while feeding the backing cloth A in a direction of an arrow. Since the bottom edge 3 is a straight and smooth ground surface, when the backing cloth A and the looper 1 move, tips of the loops B slide along the bottom edge 3 toward an opposite end to a tip of the hook throat portion 2 as shown. When the loops B are cut by knife C, the loops B tend to be pushed by the knife C toward a front corner of the hook throat portion 2 because the knife C has a shear angle D. Some of such loops may not be cut at all or partly cut. Such loops will be either cut again at different positions of a cutting edge or simply torn and will damage the backing cloth and carpet. Accordingly, cut piles thus formed tend to have widely different lengths S relative to each other. Thus, during a later shearing step, a large amount of cut piles have to be removed by shearing so that the cut piles have uniform lengths. A large amount of yarn material is thus wasted. If pile yarns are made of a material having no remaining elongation or a markedly low remaining elongation compared to ordinary tufting yarn, such as yarns for artificial turf, natural fiber yarns, and thick monofilaments, it is especially difficult to cut loops uniformly with conventional loopers having flat edges. Thus, large amounts of defective carpets tend to be produced. In a worst case, tufting is simply impossible.
An object of the present invention is to provide a looper which can form cut piles having uniform lengths, which allows a knife to reliably, precisely and cleanly cut all required loops without the yarn sliding away because of the knife shear angle D, and which has various corrugated shapes and/or a rough surface.